In the disclosure of the present invention reference is mostly made to the treatment of diabetes by delivery of insulin using a drug delivery device, however, this is only an exemplary use of the present invention.
Drug delivery devices for injection have greatly improved the lives of patients who must self-administer drugs and biological agents. Drug injection devices may take many forms, including simple disposable devices that are little more than an ampoule with an injection means or they may be durable devices adapted to be used with pre-filled cartridges. Regardless of their form and type, they have proven to be great aids in assisting patients to self-administer injectable drugs and biological agents. They also greatly assist care givers in administering injectable medicines to those incapable of performing self-injections.
Performing the necessary insulin injection at the right time and in the right size is essential for managing diabetes, i.e. compliance with the specified insulin regimen is important. In order to make it possible for medical personnel to determine the effectiveness of a prescribed dosage pattern, diabetes patients are encouraged to keep a log of the size and time of each injection. However, such logs are normally kept in handwritten notebooks, from the logged information may not be easily uploaded to a computer for data processing. Furthermore, as only events, which are noted by the patient, are logged, the note book system requires that the patient remembers to log each injection, if the logged information is to have any value in the treatment of the patient's disease. A missing or erroneous record in the log results in a misleading picture of the injection history and thus a misleading basis for the medical personnel's decision making with respect to future medication. Accordingly, it may be desirable to automate the logging of ejection information from medication delivery systems.
Correspondingly, a number of injection devices with a dose monitoring/acquisition feature has been provided, see e.g. in US 2009/0318865, WO 2010/052275 and U.S. Pat. No. 7,008,399. However, most devices of today are without it.
When a given device is provided with a position sensor it may occasionally need to be resynchronized or reset. For example, WO 2013/098421 discloses a pen device with two rotational and one axial sensor which are used for rotational resynchronization.
Having regard to the above, it is an object of the present invention to provide a drug delivery device as well as components and assemblies therefore which user-friendly, cost-effectively and reliably allows detection and storage of dose data related to use of a drug delivery device. It is a further object to provide such components and assemblies which could be used also in other applications having the same types of input.